1. Field of the Invention
The present invention relates in general to steering wheels for automotive vehicles and particularly to a core structure for reinforcement of a steering wheel.
2. Description of the Prior Art
An example of a steering wheel core structure is shown in FIGS. 6 and 7. The core structure consists of a metal hub core 105 splined to an end of a steering shaft 101 and secured thereto with a nut 103, a flange 105a integral with the hub core 105, a metal spoke core 107 secured by carbon dioxide welding A to the back face of the flange 105a and a metal hub bracket 109 secured by projection welding B to the front face of the flange 105a. With the above structure, the transfer of torque to the steering shaft 101 is performed through the spoke core 107, welded joint A and the hub core 105. The hub bracket 109 is used for installation of a horn spring, pad, etc. on the hub core 105.
The prior art steering wheel core structure requires that the carbon dioxide welding A and projection welding B be assured and reliable so that vibrations of the steering wheel will not cause breakage of the welded joint A between the spoke core 107 and the hub core 105 or the welded joint B between the hub bracket 109 and the hub core 105. For this reason, the carbon dioxide welding A and the projection welding B must be done with particular care resulting in poor work efficiency and high manufacturing cost.
Further, the prior art core structure inevitably requires the hub core 105 to have the integral flange 105a in order to make the projection welding A assured, increasing the weight of the hub core 105, which may adversely affect fuel consumption of the vehicle and cause increased vibration of the steering wheel.